It is difficult to formulate personal wash bars which can deliver sufficient skin benefit agent to provide a perceivable skin benefit and which does not at the same time affect bar processing (e.g., benefit agent may be sticky and clog machinery or may be of high viscosity and render bar composition difficult to extrude) and/or affect bar user properties (e.g., foaming).
For example, generally water insoluble benefit agents tend to reduce lather performance. Further, even when they are incorporated, efficient deposition of water insoluble skin benefit agents onto skin from bars is difficult because of high levels of water insoluble particles such as fatty acids or waxes in the bar which can compete with the benefit agent particles or inhibit deposition of desired water insoluble benefit agent on the skin.
Unexpectedly, applicants have found that when the benefit agent is delivered in the form of an adjuvant powder comprising (1) benefit agent; (2) a water soluble (or at least partially soluble) carrier; (3) water and (4) optionally a deposition/processing aid selected from the group consisting of surfactants (e.g., cocoamidosulfosuccinate, aldobionamide), cationic polymers (e.g., Merquat.RTM. 100) and hydrophilic polymers (e.g., higher molecular weight polyalkylene glycols), applicants can enhance deposition of the benefit agent (approaching levels as high as those using shower gels instead of bars) without compromising processing (and in some cases aiding processing), and further without compromising user properties such as lather volume.
Use of certain deposition polymers (e.g., cationic polymers) to enhance deposition of a water insoluble particle (e.g., an emollient oil such as silicone) is known in the context of deposition from liquid shampoo onto hair. U.S. Pat. No. 5,037,818 to Sime, for example, teaches cationics to enhance deposition on hair from shampoos.
WO 94/03152 (assigned to Unilever PLC) teaches liquid cleansers that can effectively deposit silicone oil on skin using cationic polymers.
U.S. Pat. No. 4,788,006 to Bolich, Jr. et al. teaches shampoos with silicone particles of 2 to 50 micrometers which compositions contain xanthan gum to condition hair.
The above references, however, do not teach the deposition of benefit agent from bars. Further, the references do not teach or suggest powder adjuvants comprising a benefit agent plus specific spray-dryable carrier (as well as optional deposition/processing aid which may include cationic polymers); nor do they teach or suggest combining such powder adjuvants with bar chips to form bars.
The art also discloses personal washing bars comprising cationic polymer to provide a skin conditioning affect and/or mildness (see U.S. Pat. Nos. 4,673,525 to Small et al.; U.S. Pat. No. 4,820,447 to Medcalf, Jr. et al.; and 5,096,608 to Small et al.). In these references, the cationic polymer is not used in combination with a benefit agent to form a spray dry powder adjuvant as described in the subject invention.
U.S. Pat. No. 3,761,418 to Parran, Jr. discloses detergent compositions containing both water insoluble particulate substances and cationic polymers to enhance deposition and retention of particulate substances on surface washed with the detergent composition. Specifically, enhanced deposition of antimicrobial from toilet detergent bar using cationic polymers is disclosed. Again, the reference does not teach or suggest the use of the adjuvant powder of the invention (which must contain a carrier and optionally comprises cationic polymer) for enhanced deposition of benefit agent.
In applicants copending application, U.S. Ser. No. 08/821,504 filed on the same date as the subject application and entitled "Method for Enhancing Deposition from Bars Comprising Use of Bar Adjuvant Powder Compositions Comprising Benefit Agent and Deposition Polymer", now U.S. Pat. No. 5,858,939 applicants teach bars made from an adjuvant powder which comprises cationic polymer. The adjuvants of that invention are not limited to comprise carrier with melting point above 80.degree. C., preferably above 100.degree. C. because that application is directed more broadly to the concept of first creating benefit containing adjuvants (also comprising cationic deposition aids) and coextruding with chips, any process can be used (free-drying; spray-drying). By contrast, the carrier of the subject invention must have minimum melting point in order to survive spray drying process.